Abstract
The concentration of atmospheric carbon dioxide (CO2) and polycyclic aromatic hydrocarbons (PAHs) contents in the environment have been rising due to human activities. Elevated CO2 (eCO2) levels have been shown to affect plant physiology and soil microbes, which may alter the degradation of organic pollutants. Here, we study the effect of eCO2 on PAH accumulation in a paddy soil grown with rice. We collected soil and plant samples after rice harvest from a free-air CO2 enrichment (FACE) system, which had already run for more than 15 years. Our results show that eCO2 increased PAH concentrations in the soil, and we link this effect to a shift in soil microbial community structure and function. Elevated CO2 changed the composition of soil microbial communities, especially by reducing the abundance of some microbial groups driving PAH degradation. Our study indicates that elevated CO2 levels may weaken the self-cleaning ability of soils related to organic pollutants. Such changes in the function of soil microbial communities may threaten the quality of crops, with unknown implications for food safety and human health in future climate scenarios.
Highlights
Due to global industrialization and human population growth, atmospheric concentration of carbon dioxide (CO2) has raised from approximately 280 ppm in pre-industrial times to approximately 400 ppm today, and it is expected to continue increasing in the future [1]
We studied the effects of Elevated CO2 (eCO2) on polycyclic aromatic hydrocarbons (PAHs) degradation by assessing soil microbial community structure through high-throughput sequencing and mineralization of 14C-PAHs by fresh soils that had been conditioned by the different CO2 treatments
Among all PAHs, anthracene was increased the most at eCO2 in 2015 (5.36-fold compared to aCO2), and acenaphthylene was increased the most at eCO2 in 2016 (3.37-fold compared to aCO2; S1 Table)
Summary
Due to global industrialization and human population growth, atmospheric concentration of carbon dioxide (CO2) has raised from approximately 280 ppm in pre-industrial times to approximately 400 ppm today, and it is expected to continue increasing in the future [1]. Volatilization and chemical degradation are involved during the removal process of PAHs from soils, biodegradation is the major degradation process of PAHs, which depends on soil microbial communities and environmental conditions [4].
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